title: Synergistic kinetic interactions between components of the phosphorelay controlling sporulation in Bacillus subtilis.
abstract: The four individual phosphotransfer steps in the multicomponent phosphorelay system controlling sporulation in Bacillus subtilis have been characterized kinetically using highly purified samples of the individual protein components in vitro. The autophosphorylation of KinA is the initial occurrence, and a divalent metal ion is required. KinA-mediated phosphotransfer, which displays a 57,000-fold preference (kcat/Km) for catalysis of Spo0F-P formation relative to Spo0A-P formation, is shown to proceed via a hybrid ping-pong/sequential mechanism with pronounced (> or = 40-fold) substrate synergism by Spo0F of KinA autophosphorylation. In addition, evidence is presented for formation of an abortive KinA.Spo0F complex. Kinetic parameters derived for Spo0F-P and Spo0A as substrates for Spo0B, the second phosphotransferase in the phosphorelay chain, indicate that Spo0B-mediated production of Spo0A-P is 1.1-million-fold more efficient (kcat/KSpo0A) than the direct KinA-mediated process. A rationale is presented for a four component cascade as the means for controlling sporulation, which focuses on the utility of synergistic interactions among the phosphorelay components that may be modulated by environmental stimuli.
authors.affiliation: Scripps Research Institute, R. W. Johnson Pharmaceutical Research Institute, La Jolla, California 92037, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Grimshaw
authors.forename: S
authors.initials: S
authors.lastname: Huang
authors.forename: C G
authors.initials: CG
authors.lastname: Hanstein
authors.forename: M A
authors.initials: MA
authors.lastname: Strauch
authors.forename: D
authors.initials: D
authors.lastname: Burbulys
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: J A
authors.initials: JA
authors.lastname: Hoch
authors.forename: J M
authors.initials: JM
authors.lastname: Whiteley
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D001667:Binding, Competitive; D004357:Drug Synergism; D007700:Kinetics; D010766:Phosphorylation; D010770:Phosphotransferases / Q000502:physiology; D011494:Protein Kinases / Q000502:physiology; D015290:Second Messenger Systems / Q000187:drug effects; D012808:Sigma Factor; D013171:Spores, Bacterial / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D013997:Time Factors; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; C080951:Spo0F protein, Bacillus subtilis; D014157:Transcription Factors; C075521:kinA protein, Bacillus subtilis; C092468:spoIIR protein, Bacillus subtilis; C030069:spore-specific proteins, Bacillus; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D011494:Protein Kinases; C002630:alpha,beta-methyleneadenosine 5'-triphosphate